caetweight



2 Sheets-Sheet l.

(No Model.)

D. J. CARTWRIGHT.

SAFETY FUSE ECR ELECTRICAL DEVICES.

Patented Sept. 28,1897.

sa las WITNEESEE. INVEN-rmr @mf/M M @223% (No Model.) 2 Sheets-Sheet 2. D. J. CARTWRIGHT. SAFETY FUSE ECR ELECTRICAL DEVICES. No. 590 ,750.

Patented Sept. 28, 1897.

F.. A l W UNITED STATES DAVID J. CARTWRIGIIT, OF BOSTON,

PATENT OFFICE.

MASSACHUSETTS, ASSIGNOR TO 'l'llE ELECTRICAL SAFETY COMPANY, OF SAME PLACE.

`SAFETY-.FUSE FOR ELECTRICAL DEVICES.

SPECIFICATION forming part of Letters Patent No. 590,750, dated September 28, 1897.

nppnt-.iuon'manpai 19,1397.

To all, 'wh-0111- It nur, rulwcrrl.:

lle it known that. I, DAVID J. CAn'rwRIen'r, of Boston, in 'the county of Suffolk and State of Massachusetts, have invented a' new and useful Improvement ingSafety-F uses for Electrical Devices, of which the following` taken in connection with the accompanying drawings, is a specification.

This invention relates to inclosed fuses, and has for its object, first, the production of a safety-fuse which when connected in a circuit can be handled or touched withoutthe possibility of the person touching the device coming into contact with any part of the cirv cuit; second, the production of a safety-fuse which can be used in places where there are inflammable or explosive gases or substances without the possibility of causing' the ignition or explosion of these gases or substances; third, the determination at a definite part of the fuse-wire of the rupture of the same by the fusing elfect of thc heat produced by the increased current through the f use-wire; fourth,

the prevention of noise when the fuse-wire is ruptured by thc effect of the increased current; fifth, the prevention of the formation 'of an arc at thc point where the fuse-wire breaks; sixth, the absorption and distribution of the gases or other substances produced bythe fusing of the fuse-wire, whereby the force of any explosive action attending this fusing is rendered harmless; seventh, the capability of removing from the-inclosing tube or case the substances produced by the fusing of the fuse-wire; eighth, the regulation of the carrying capacity of the fuse wire, whereby its rupture by the fusing effect of the increased current may be predetermined for any strength of current and for any period of time; ninth, the production of .means for obtaining with an inclosed fuse-wire an indication that a rupture of the fuse-wire has occurred. I attain these results by the de vices hereinafter fully described in this specification and illustrated in the accompanying drawings, and which devicesembody the principle of my invention.

In the drawings, Figure l is a longitudinal sectionalviewof one form of t'hesedevicesand shows the fuse-wire as unbroken and the cov vice.

sarah no. 032,738. uio man.)

ering device held in position by the'fuse-wire. Fig. 2 is a similar longitudinal sectional view of the same device and shows 'the'fuse-wire broken and the covering device moved .to cover Vthe perforation in the partition and to give an indication that a rupture of the fusewire has occurred. Fig. 3 is a detached view in elevation of the covering device used in this embodiment-of the invention and shows the recess in the covering device. Fig. 4 is 6o a detached sectional view of this covering device. Fig. 5 is auend view of 4the tube or case. Fig. G is a longitudinal sectional view of a part of another form of device embodying the principle of Iny invention and shows another form of covering device. Fig. 7 is a horizontal sectional view of that part of the device which contains the covering device. Fig. 8 is a plan view of the indicator operated by the covering device. Fig. 9 is a sec- 7o tional longitudinal view of part of the de,- vce and shows another form of covering de- Fig. 10 is a frontview of this covering device,showing its position when the fusewire is unbroken. Fig. 11 is a sectional lon-A 7 5 gitudinal view of part of thcdevice and shows I still another form of covering device. Fig.

12 is a longitudinal sectional view of part of device and shows a means for giving an indication that thefuse-wire is broken. Fig. 8o 13 isa longitudinal view in elevation of the tube or case and the means for supporting the same when in use. Fig. 14 is a 1ongitudinal sectional view of au embodiment of the principle of my invention, in which embodiment the covering and indicating devices are not used. Fig. 15 is an end view of the same. Fig. 16 is a perspective view of a terminal.

In the several tigures the same numerals refer to the same parts.

Referring tothe drawings, 1 is a tube or case, and 2 `is the fuse-wire passing through the same and which fusewire may be of the usualform or material or of any suitable form or material. This case may becylindrical or rectangular or of any coIwenient-f-foim. It may be made of any suitable material, but if made of a conducting material its ends should be of an insulating material or'insulation should be afforded for the torminalsto which Ico the fuse-wire is attached. A convenient material for the tube or case is fiber. A convenient size for general purposes is' about three inches in length by three-quarters of an inch in diameter, as shown in the drawings, but it may be of larger or of smaller dimensions as may be found desirable.

The ends of the tube or case are closed and a convenient means of accom plishing this result is by means of the end pieces 3, each of which may be held in position by an insulated ferrnle 4 or in any other suitable manner. In each of the ends of the tube or case is inserted a piece of metal 5, round or square in Isection and in the form of a rod or strip or of any other convenient form. This piece may have in it a longitudi-nal perforation for the reception of thefnse-wire or the fuse-wire may be otherwise attached to the piece 3. This piece forms a suitableV terminal forthe fuse-wire by means of which connection of the fuse-wire is made with the conductingwire of the circuit-as for example, by the insertion of these terminals in suitablesoekets in the standards 7, supported upon a suitable base-plate 8, o which standards the conducting-wires are connected in any suitable manner. These standards are best made of sufiicientheight to prevent the possibility of contact of the conducting-wire with the tube or case. Y

A boss 9 of insulating material may be placed upon the end of the tube or ease in order to prevent contact of the tube or case with the supportfor the conducting-wire.

The inner ends ofthe terminals project into the adjacent filling and act to conduct heat away from the fuse-wire at that part of the same so as to prevent the possibility of the 4fuse-wire fusing near the end of the case.

to conduct away from that part of the fuse.

ivire which passes through this filling the heat produced by the passage of the current A through the fuse-wire.

I can use several substances for the filling lO-as for example, asbestos, plaster-of-paris, oil, or paratiin*aud I do not confine myself to 'any particular substance, provided it is different from the f use-wire and acts t'o conduct heat away from the same, but I prefer asbestes, and a convenient manner for nsing lthis material is by winding a strip of sheetasbestos around a part of 'the fuse-wire until such a thickness of covering is secured that when the asbestos-covered wire is inserted i'n'to tlre tube crease the asbestos will be packed or firmly held in the end of the tube or case.

Asbestos is insulating, isnon-inflannnable, is sufficiently heat-conducting to conduct some of the heat away from this part of the fuse-wire, which is in contact with the asbestos, and by its porous nat-ure it acts to absorb and hold the gases and other substances p'roduced by the fusing and combustion of the fuse-wire by the heat produced by an increased current passing through the fusewire, and by its elasticity it yields to the pressure of the gases, and thus, in connection with the' absorption of the gases and other substances produced by the fusingand eombustion of the fuse-wire, tends to prevent harmful results from any explosive action when this fusing and combustion takes place. It is also coherent and can be packed around the fuse-wire, so as to enable a definite airspace to be formed in the inclosing tube or case wilhout the use of partitions or of a drum.

Between each of the filled ends of the tube or case is a space 11, through which the fusewire passes, and in order to insure the rupture of a fuse-wire of the same conductivity by any predetermined strength of current and after the passage of a current for any Y predetermined time this space must be of definite dimensions, as any variation in the dimensions of this space will effect thc carrying capacity of the fuse-wire to the point of rupture by an increased current, and it is important in safety-f uses for electrical circuits that the carrying capacity of the safety-fuse should be accurately known.

If the filling material is capable of being compacted into eachend of the tube or case, the definition with accuracy of the space 1l, between the fillings 9, can-beefected without a partition, but as some ot' the materials IOO reg

which may be used for filling must beotherwise retained 'in the end of the tube or ease may be formed.' The proper insulation of' the fusewire in this partition is obtained either by making this partition of an insn' lating material or in' any other suitable manner.

The partitions may be separable from the case, and they fit air-tight within the same,

and may be held in position in any suitable manner and be adjustable, thus permitting a variation in the length of the 'air-space for the purpose of changing the carrying capacity of the fuse-wire.

As the fuse-wire in the space 11 is ont .of

contact with any heat-conducting material rupture of the fuse-wire by the heat produced by the increased current passing through the fuse-wire will take place at the part of the fuse-wire in the space 11 instead of at any other part of the fuse-wire, and the gases or other materials produced by this fusing of the f use-wire will be mainly formed in this space 11. For the further purpose of preventing the passage of an arc from this space through the perforation in the partition when the fusewire is ruptured in this space 11 I may use a device which is normally held in position by the fuse-wire when this fuse-wire is unbroken against a force acting to move this ldevice, which device automatically covers the perforation in the partition when the fuse-wire is ruptured', as in Letters Patent No. 441,933, granted to me December 2, 1890, and in this part of the tube or case I place the means whereby an indication maybe given that the rupture of the fuse-wire has occurred. The means for giving this indication may form a part of the covering device and may be operated thereby, or it may be an independent device, and I may dispense with either or both of these devices.

Various devices may be adopted for both purposes.

In Figs. 1 and 2 I have shown the device for covering the perforation in the partition through which the fuse-wire passes as consisting of a block 13, of'an insulating material perforated for the passage of the fuse-wire and held in position by the fuse-wire when the latter is intac and moving 'transverseiy to the tube or case i in substantial contact with or adjacent to the inside surface ci the partition in a tube formed by the partition, a collar 1t on the inside of the 'tui and a rim 15, each around Opps. in the tube or case l ou oppcsie same. The ends of 'the trans-verse tui are each preferably covered with. a rap li, and i one or both ends cf these caps able in order that the block y moved from the tube or case the removal from the space can he EGGS produced by the fusing of ine sti-whe. Gn one end of the block if? is a roti procction lwhich passes through the cap nti when the fuse is unbroken s listan l to the outcrsurface of ih lap ond of the block 2.12 a suitable is arranged, which acts when the hier 13 is permitted to move by the breaking -1 the instr vvire to move this biock, so that covers the perforation in the partition and aise causes the projection from the surface of the cap 16 of the rod or other device or atta ched to the block '13, thus'at'fording a visual indication that a rupture of the fuse-wire has occurred.

Instead of the rod 17 I can use any other suitable device.

I have shown a helical spring 18 in a socket 19 in the block 13, but it is obvious that other .fino hns permit forms or arrangements of springs may be used or any other means for moving the block 13 on the release of the same.

A longitudinal recess 20, surrounding the fuse-wire, is preferably formed in the block 13, open toward the space l1 and tapering toward the adjacent partition 10. The4 eiect of this recess is to bring upon that part of the fuse-wire which is near the perforation in the partition the pressure of the spring which moves the block 13, and thus cause a tendency of the fuse-wire to rst rupture at that pointwhen the fuse-wire is softened by the heat of the increased current. This recess also acts to receive the gases produced when the fuse-wire is/fused, so that the block will have a tendency to be moved by the expansive force of these gases.

The movement of the covering device produced when the block is released by the rupture of the fuse-wire may be made to open or close an elect-ric circuit for the purpose of operating electric magnetic devices for giving a visual or an audible indication, or both, that a rupture of the f use-wire has occurred, or it may be made to operate or release other mechanism for the same purpose.

I have shown only one covering device, but two or more may be used.

Instead of a perforation, a transverse slot may be used for the passage of the f usc-wire through the covering-block.

In the covering device shown in Figs. G and 7 the block 13 rotates in the transverse tube, this rotation being effected by a suitable spring 21 or by any other suitable means when the fuse-wire breaks. The visual indication may he given by the movement of an index .22 on the outside of the tube or case and attach if the block. The recess acts to loca e point of rupture of the fuse wire near 'the perforation in the partition.

In the dev hows in Figs. 9 and 10 the transversfx whe ,s dispensed with and on each end of r ring-block 13 is a rod which pr; .rsversely through the tube or case.

in the covering device shown in Fig. il the fuse-wire rests upon the end of the 13, and this bisch is beveled oi toward the partiticn. The withdrawal of a` rod 24, attached to the blot-,k 13, and normally projet-1'.u ing through the side of the tube or case` ai fords a vi.. .ai indication that rupture of the fuse-wire occurred, and this rod may made te effect the operation of 4an electromagnetic dovice or other mechanism for giving a visuai or audible indication, or both, that rupture of the fuse-wire has occurred. A visual or an audible indication, or both, of this fact may be afforded by the device shown in Fig 12, for which device a rod 25, moving by the force of a spring 26,in a case 27,attached to the outside of the tube or case, i's provided with a loop or hook 28, through which loop or hook the fuse-wire passes, and when thefuse- IOOv wire is intact the rod 25 is prevented from moving, but when the fuse-wire is ruptured the spring .l is allowed to act to move the rod.

Other forms of devices operating to afford a visual or audible indication of the rupture of the wire may bc uscd.

In'the device. shown in Figs. 13 and 14 the covering and indicating devices are not used.

For the purpose of removing the material produced in the fusion of the fuse-wire perforations 29 may be formed in the space 11 of the tube or ease, normally closed by any suitable means-as, for example, by the screws 30.

IIaving thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

l. The combination, substantially as set forth, of an air-tight tube or case inclosing the entire fusible metal and tightly closed at each end by inflexible material, a coherent filling at each end of the tube or case of a different material from the fuse-wire and acting to conduct away from that part of the fuse-wire which passes through the filling the heat produced by the passage of the current through the fuse-wire at that part and to absorb the gases and other substances generated when the fuse-wire melts, a definite air-space between the fillings; and a fuse-Wire passing through the fillings and the air-space. p

2. Tile combination, substantially as set forth, of an airtight tube or case inclosing the entire f usiblel metal and tightly closed at each end by inflexible material, a filling of asbestos at each end of the tube or case, a definite air-space between the fillings, and a fuse-wire passing through the fillings and the air-space. g

3. The combination, substantially as set forth, of an air-tight tube or case inclosing the entire fusible metal tightly closed at cach end by inflexible material, transverse inflexible partitions dividing the tube or case into sections of a definite length and perforated solely Where the fuse-wire passes through the partition, a fuse-wire passing through the tube or case and partitions, a filling at each end of the tube or case of a different material from the fuse-wire and acting to conduct away from that part of the fuse-wire which passes through the filling the heat produced by the passage of the current through the fuse-wire at that part and to absorb the gases and other substances generated when the fuse-wire melts, and a definite air-space between the end sections.

4. The combination, substantially as set forth, of an air-tight tube or case inclosing the entire fusible metal and tightly closed at each end by inflexible material, transverse, inflexible movable partitions dividing the tube or case into sections of a. definite length and perforated solely where the fuse-wire passes through thc partition, a fuse-wire passing through the tube or case and parti tions, Va filling at each end of the tubo or case of different material from the fuse-wire and acting to conduct away from that part of the fuse-wire which passes through the filling the heat produced bythe passage of the current through the fuse-wire at that part and to absorb thc gases and other substances generated when the fuse-wire melts, and a definite air-'space between the end sections.

5. The combination, substantially as set forth, of a tube or case, a fuse-wire passing through said tube or case, a rod extending transversely through the case and normally held by said fuse-wire when said fuse-wire is unbroken and a spring acting when the fuse-wire is broken to cause the projection of the rod.

il. The combination, substantially as set forth, of a tube or case, a fusewire passing through said tube or ease, a transverse partition in said tube or case through which partition the fuse-wire passes, a movable-device normally held in position by the fuse-wire when said f use-wire is unbroken, means acting when thc f usc-wire is broken to move the device to cover the perforation" in the partition through which the fuse-wire passes, and means operated bythe movement of the covering device to give an indication that the fuse-wire is broken.

7. The combination, substantially as set forth, of a tube or case, a fuse-wire passing through said tube or case, a transverse partition in said tube or case through which partition the fusewire passes, a movable device adjacent to the inner surface of the partition and thro n gh which device the f use-wi re passes and normally held in -position by the fuse- .wire when said fuse-wire is unbroken, and moving when the Wire is broken adjacent to the inner surface of the partition to cover the perforation in the partition through which the f use-wire passes, a perforated recess xin this device tapered toward the partition and surrounding the fuse-wire.

8. The combination, substantially as set forth, of a tube or case, a fuse-wire passing through said tube or ease, a transverse partition in said tube or case through which partition the fuse-wire passes, a block of insulated material perforated for the passage of the fuse-wire and adjacent to the inside surface of the partition and transversely movable, a covered transverse tube for the movement of said block, a spring acting to move said block transversely when the wire is broken in the space adjacent to the inner surface of the partition, and a device attached to the block and projecting from the tube or case, when the block moves on the rupture of the fusewire il. The combination, substantially as set forth, with an air-tight tube or case inclosing the entire fusible metal and tightly closed at cach end by an inflexible material,I an m5- lated metallic terminal forV the fuse-wire and projecting respectively from each end of th tube or case and extending within the same, supports for the terminals, means for .preventing the contact of the case with the supports, ferrnles .or caps on each end of the tube or case nd insulated from the adjacent terminals. l

10.i The. combination, substantial-ly as set forth,.with an air-tight tube or case inclosing the entire fusible m'etal and tightly closed at each end by an inflexible material, an insulated metallic terminal for the fuse-wire and projecting respectively from each cnd of the tube or case and extending within the same, supports for the terminals, nn insulating-boss on the outside of each end of the tube o1' case for preventing the contact of the case with the supports, ferrules or caps on each end of the case and insulated from the adjacent terminals.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, on this 16th .day of April, A. D. 1897.

DAVID J. CARTWRIGHT.

Witnesses:

EMERY GROVER, A. D. KINGSBURY 

